Convection barrier

ABSTRACT

A convection barrier for a freezer is disclosed. The convection barrier may include a foil having at least one opening therein, storage and transport means for storing and moving the foil so as to transport the at least one opening to a desired position allowing access through the at least one opening to the interior of the freezer at the desired position and tensioning means for continuously keeping the foil in a tensioned state.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to European Patent Application No. 08160042.1, filed Jul. 9, 2008, the entire contents of which are herein incorporated by reference in their entirety.

FIELD

Embodiments of a convection barrier are described herein. In particular, embodiments of a convection barrier having a foil, storage and transport means and tensioning means are provided. More particularly, the convection barrier embodiments disclosed herein may be used in connection with a freezer.

BACKGROUND

In clinical studies a wide variety of assays can be carried out to answer questions related to diagnosis (e.g., biomarker), treatment (e.g., efficacy of a drug) and prevention of diseases.

Large sample collections of biological samples can be established, e.g., within the context of clinical studies. Such biological samples may include without limitation blood samples (e.g., whole blood, plasma, serum), urine samples, tissue samples, cells (e.g., cell lines, primary cell cultures), proteins, DNA, RNA (e.g., RNAi, mRNA), or antibodies.

An automated facility for storing biological samples at −80° C. is used in the UK biobank and is described, for example, in the article “Designing and implementing a large-scale automated −80° C. archive,” by Justin M. Owen and Peter Woods, published in the International Journal of Epidemiology 2008; 37: i56-i61 (doi: 10.1093/ije/dym293). The store described therein comprises a system of drawers arranged in a manner so as to form a shelf, which allows robotic access to the biological samples whilst maintaining storage conditions. The drawers can be opened individually by the robot pulling the respective drawer outwards so as to allow access to the interior of the drawer where the biological samples are stored.

However, this system has disadvantages. First, at its front surface each drawer is provided with a block made of styrene in a manner such that the styrene blocks of adjacently arranged drawers abut against one another. Upon opening an individual drawer by pulling the drawer outwardly, there is inherently the risk of an adjacently arranged drawer also being pulled out, even though not intended, thereby causing an unwanted temperature rise. Also, the total leakage of cold air is comparatively high because the system does not have a separate front door for closing the system.

Cooling of a complete humidity controlled room for storing biological samples as described above to about −80° C. is generally feasible. However, standard handling devices, such as for example robots, usually do not work properly at such temperatures. Therefore, particularly for long-term storage of biological samples, specific −80° C. freezers are typically used.

These specific freezers for long-term storage usually have a thermally insulating door which separates the environment outside the freezer (e.g., a −20° C. environment) from the −80° C. interior of the freezer. In a so-called “robotic store,” a plurality of such freezers is arranged as well as a robot for taking the samples out of each freezer. As mentioned above, the robot cannot be arranged in the −80° C. environment. Instead, the robot is arranged outside the freezers in the warmer −20° C. environment where it is capable of working properly. However, particularly with conventional upright standing freezers certain problems may arise in this configuration. First, upon having opened the door in order to allow the robot to access the interior of the freezer, the −80° C. cooled air flows out of the interior of the freezer while at the same time −20° C. air flows from the environment into the interior of the freezer, leading to a rise in temperature and humidity within the interior of the freezer. This is particularly the case because the door of the freezer usually must remain open for a considerable period of time until the desired one or more biological samples have been removed. Secondly, the flow of −80° C. air out of the freezer and −20° C. air into the freezer creates two effects: (i) a negative pressure that makes the door extremely difficult to open again until the negative pressure is equalized by inflowing air through the sealing of the door of the freezer, which usually takes a considerable period of time (e.g., up to 30 minutes); and (ii) the cooling down of the −20° C. air which is more humid than the −80° C. air results in formation of ice within the freezer, requiring defrosting of the freezer more often.

It is therefore an object of the invention to overcome the aforementioned disadvantages and to provide suitable measures to avoid or at least greatly reduce the above-described scenarios. Also, loss of energy should be reduced to a minimum while at the same time frequent access to the stored biological samples should be possible.

This object is achieved through the convection barrier embodiments disclosed herein and through a freezer comprising such convection barrier embodiments.

SUMMARY

Disclosed herein are embodiments of a convection barrier. Some embodiments of the convection barrier are particularly well-suited for use in a freezer. Exemplary embodiments of the convection barrier may include a foil having at least one opening therein, storage and transport means for storing and moving the foil to transport the at least one opening to a desired position to allow access through the at least one opening to the interior of the freezer at the desired position and tensioning means for continuously keeping the foil in a tensioned state.

In some embodiments, the foil may cover the opening to the interior of the freezer so that no cold air (e.g., −80° C.) may flow out of the interior of the freezer or that only small amounts of cold air may flow out of the freezer when the freezer door is open. However, it must be possible to access a desired sample or samples stored in the interior of the freezer. In some embodiments, this can be achieved by allowing access (e.g., by a robot) to a desired one or more samples through an opening or openings provided in the foil. According to some embodiments, because a sample may be stored at any location in the interior of the freezer, the opening must be movable to the position where the respective sample is located or stored. To move the one or openings, some embodiments of the convection barrier may include storage and transport means for storing and transporting the foil so that the opening in the foil can be moved to the position and stored in this position to allow access to a sample through the opening. To avoid jamming of the foil and in order to keep the air cold (e.g., −80° C.) within the interior of the freezer, tensioning means are provided for keeping the foil in a tensioned state during storing and transporting. Thus, outflow of cold air (e.g., −80° C.) out of the interior of the freezer and backflow of warmer air (e.g., −20° C.) from the environment into the interior of the freezer is prevented or at least greatly reduced. Accordingly, the above-described disadvantages of temperature rise in the interior of the freezer and negative pressure making the door extremely difficult to open are prevented or at least greatly reduced by the convection barrier embodiments disclosed herein.

In some embodiments of the convection barrier, the storage and transport means may comprise two reels to which the opposite ends of the foil are mounted and between which the foil extends. Some embodiments of the convection barrier may also include a drive for rotating the reels so as to wind up or unwind the foil from the respective reel to transport the at least one opening to the desired position.

Some embodiments of the convection barrier may comprise a frame having at least one opening, the frame being insertable into the foil at a location between the ends of the foil such that the at least one opening of the frame for allowing access to the interior of the freezer can be transported to any desired position. According to some embodiments, the frame may be rigid and stable to reliably position the opening at a desired location so as to allow access (e.g., by a robot) to the interior of the freezer through the at least one opening.

In some embodiments of the convection barrier, the drive may comprise a motor connected to one of the at least two reels, and the tensioning means may comprise a return spring connected to the other one of the at least two reels for continuously keeping the foil in a tensioned state. In exemplary embodiments, that reel to which the motor is connected may be driven by the motor while the other reel is acted upon by the return spring so that the foil is always kept in a tensioned state. This configuration is advantageous because it allows various additional embodiments to be conceived, as discussed below.

In some embodiments, the drive may further comprise a belt engaging both of the two reels, and the return spring may be a spring having a low spring rate. Since the belt already provides for synchronization of the two reels, i.e., the reels are driven with the same speed, the return spring must only have a low spring rate in order to keep the foil in a tensioned state. While the outer diameter of the respective reel with the foil wound around it continuously changes during movement of the foil, the return spring maintains the foil in a tensioned state.

In some embodiments, the return spring may be a spring having a high spring rate. Particularly in the case where there is no mechanical connection between the two reels (e.g., by means of the aforementioned belt), it is advantageous that the spring has a high spring rate in order to make sure that the foil is always kept in a tensioned state.

One example of a return spring having a high spring rate includes without limitation a torsion spring. In some embodiments, the torsion spring can be arranged within a hollow reel to achieve the advantages of the convection barrier according to some embodiments of the invention.

In some embodiments of the convection barrier, the drive and the tensioning means may comprise two motors. Some embodiments may include one of the two motors being connected to one of the two reels and the other motor being connected to the other one of the at least two reels. The convection barrier may also, according to some embodiments, comprise a control unit for operating the two motors in an asynchronous manner so as to continuously keep the foil in a tensioned state. In some embodiments, the control unit may have two functions: First, it may control the speed of the reels, depending on whether the reel is winding the foil up or unwinding the foil, depending on how much of the foil is still wound around the respective reel. The control unit may also function, according to some embodiments, to drive the two motors in an asynchronous manner so as to make sure that the foil is always kept in a tensioned state. In this embodiment, one of the two motors may act in a manner similar to the aforementioned mechanical return spring, depending on the direction of movement of the foil.

Possible materials for the foil may include without limitation, polytetrafluoroethylene or a mesh, e.g., a glass mesh, coated with polytetrafluoroethylene. Polytetrafluoroethylene is readily available on the market and is capable of fulfilling the requirements with regard to the operational demands, in particular with respect to temperature, mechanical stress and durability.

As already mentioned above, embodiments of the convection barrier may be used in connection with a freezer. In some embodiments, the freezer may comprise a housing and a door. In some embodiments, the housing may have an opening allowing access to the interior of the freezer through the opening when the door of the freezer is open. Embodiments of the freezer preferably further comprise a convection barrier as described above. The convection barrier may be arranged, according to some embodiments, such that the opening allowing access to the interior of the freezer is covered by the foil.

In one particularly advantageous embodiment of the freezer, one or more motors, or a belt, of the convection barrier may be mounted to the freezer outside its housing. This is advantageous because the motor or motors work well in the environment outside the freezer, e.g., in a −20° C. environment, while this is not the case in the environment in the interior of the freezer, e.g., in a −80° C. environment. Also, maintenance of these components is possible in the environment outside the freezer (e.g., −20° C.).

BRIEF DESCRIPTION OF THE FIGURES

Further advantageous aspects of the invention will become apparent from the following description of embodiments of the convection barrier with the aid of the Figures 1-15.

FIG. 1 shows a cross-sectional side view of a freezer in accordance with some embodiments of the invention with an embodiment of the convection barrier according to the some embodiments of invention mounted thereto.

FIG. 2 shows a front view of an embodiment of the convection barrier according to the invention.

FIG. 3 shows the upper reel of the convection barrier to which the foil is mounted according to some embodiments of the invention.

FIG. 4 shows the lower reel of the convection barrier to which the foil is mounted according to some embodiments of the invention.

FIG. 5 shows a perspective view of an embodiment of the freezer according to the invention with an embodiment of the convection barrier according to the invention mounted thereto.

FIG. 6 shows the detail VI of FIG. 5 in an enlarged view.

FIG. 7 shows the detail VII of FIG. 5 in an enlarged view.

FIG. 8 shows the detail VIII of FIG. 5 in an enlarged view, partially broken away.

FIG. 9 shows the detail IX of FIG. 5 in an enlarged view, partially broken away.

FIG. 10 shows a perspective view of an embodiment of the freezer according to the invention with an embodiment of the convection barrier according to the invention mounted thereto.

FIG. 11 shows the detail XI of FIG. 10 in an enlarged view.

FIG. 12 shows the detail XII of FIG. 10 in an enlarged view.

FIG. 13 shows a perspective view of an embodiment of the freezer according to the invention with an embodiment of the convection barrier according to the invention mounted thereto.

FIG. 14 shows detail XIV of FIG. 13 in an enlarged view.

FIG. 15 show detail XV of FIG. 13 in an enlarged view.

DETAILED DESCRIPTION

FIG. 1 shows a cross-sectional side view of a freezer 1 according to the invention with a convection barrier 2 mounted thereto, with the door of the freezer 1 not being shown in FIG. 1 for the sake of simplicity. Freezer 1 comprises a housing 10 having an opening 11 at the front side of the freezer (in FIG. 1 on the right hand side). A plurality of compartments 13 are arranged in the interior 12 of freezer 1. In the third compartment from the bottom, a drawer 3 is represented by way of example which carries a plurality of trays 30 in which, e.g., microtubes (not shown), may be arranged in which the samples are stored. Convection barrier 2 comprises a foil 20, the two opposite ends of which are mounted to two elongate reels, an upper reel 21 and a lower reel 22, so that the foil extends therebetween. Convection barrier 2 is mounted to freezer 1 such that foil 20 of convection barrier 2 covers the opening 11 of freezer 1 so that the flowing out of cold air (e.g., −80° C. air) from the interior 12 of freezer 1 is prevented or is at least greatly reduced. As can be seen in FIG. 1, in order to get access to the respective drawer 3 carrying the tray 30 with the desired sample, a frame 23 comprising one or more openings 230 (see FIG. 2) is inserted in the foil at a location between the two ends of the foil 20 such, that the one or more openings 230 allow access to drawer 3 carrying the tray 30 with the desired sample.

One embodiment of convection barrier 2 according to the instant invention is shown in FIG. 2. In the embodiment shown in FIG. 2, outer frame 24, foil 20, and frame 23 carrying the one or more openings 230 (e.g., four openings) can be seen. Accordingly, columns (e.g., four) of drawers may be arranged in the interior of freezer 1. In order to get access to the various compartments 13 in the interior 12 of freezer 1 where the respective drawer 3 carrying the tray 30 with the desired sample is arranged, frame 23 must be movable up and down in order to get to the respective location, as this is indicated by the arrows in FIG. 2. Frame 23 is preferably made from metal, e.g., aluminium, so as to reliably and stably position the openings 230 at the desired location in front of the respective drawer 3. For proper functioning, foil 20 should be kept in a tensioned state.

FIG. 3 shows the elongated upper reel 21 with the one end of foil 20 mounted thereto in an enlarged view, while FIG. 4 shows the lower reel 22 with the opposite end of foil 20 mounted thereto. Through rotation of the upper and lower reels 21, 22 foil 20 can be wound up or unwound from the respective reel. This can be achieved in various ways, as explained in more detail below.

FIG. 5 shows a perspective view of an embodiment of a freezer according to the instant invention comprising a specific embodiment of a convection barrier according to the invention. In this embodiment, like parts are assigned like reference signs but a letter “a” is added. Accordingly, freezer la comprises a housing 10 a and a door 100 a which is shown in its open position. Convection barrier 2 a comprises an outer frame 24 a, a foil 20 a with a frame 23 a carrying one or more openings 230 a. Foil 20 a extends between the two ends thereof which are mounted to elongate upper reel 21 a and elongate lower reel 22 a, respectively. A motor 25 a drivingly engages an axle 210 a which itself is connected to elongate upper reel 21 a for rotatably driving upper reel 21 a. A control unit 26 a is provided for operating motor 25 a. Lower elongate reel 22 a is also connected to an axle 220 a. Two belt pulleys 211 a and 221 a (see also FIG. 6 and FIG. 7) are mounted to axles 210 a and 220 a, respectively. An endless belt 27 a is guided over belt pulleys 211 a and 221 a and engages the pulleys 211 a and 221 a, thus mechanically connecting axles 210 a and 220 a. Accordingly, as motor 25 a rotatably drives axle 210 a (and upper reel 21 a) pulley 211 a is also rotated and via belt 27 a causes pulley 221 a to rotate, thus rotating axle 220 a (and lower reel 22 a). Accordingly, upper and lower reels 21 a, 22 a essentially rotate with the same speed.

FIG. 6 shows detail VI of FIG. 5 in an enlarged view. Although already shown in FIG. 5, FIG. 6 more clearly shows that motor 25 a and control unit 26 a as well as drive pulley 211 a and belt 27 a arranged on axle 210 a are located outside the freezer, e.g., in the above-mentioned −20° C. environment where they work properly and can be maintained. The same holds true for drive pulley 221 a arranged on axle 220 a, as seen in greater detail in FIG. 7.

In FIG. 8 the detail VIII of FIG. 5 is shown in an enlarged view and partially broken away. It can be seen how foil 20 a enters beneath outer frame 24 a and can be wound up or unwound from reel 21 a. FIG. 9 shows the detail IX of FIG. 5, also partially broken away. From FIG. 9 it can be seen that a torsion spring 28 a arranged in the interior of reel 22 a, which in some embodiments may be hollow. Torsion spring 28 a is a weak spring which is always in a tensioned state, even when frame 23 a carrying the openings 230 a is in its lowermost position, so that foil 20 a is always kept in a tensioned state.

FIG. 10 shows a further embodiment of the freezer according to the invention comprising a specific embodiment of a convection barrier according to the invention. In this further embodiment, like parts are again assigned like reference signs but a letter “b” is added. Accordingly, freezer 1 b comprises a housing 10 b and a door 100 b which is shown in its open position. Convection barrier 2 b comprises an outer frame 24 b, a foil 20 b with a frame 23 b carrying one or more openings 230 b. Foil 20 b extends between the two ends thereof which are mounted to elongate upper reel 21 b and elongate lower reel 22 b, respectively. A motor 25 b drivingly engages an axle 210 b, as can be seen in FIG. 11 showing detail XI of FIG. 10 in an enlarged view. Motor 25 b is connected to elongate upper reel 21 b for rotatably driving upper reel 21 b. A control unit 26 b is provided for operating motor 25 b. In the interior of lower reel 22 b which is embodied as a hollow reel, a torsion spring 28 b is arranged.

This can be seen more clearly in FIG. 12 showing detail XII of FIG. 10, also partially broken away. From FIG. 12 it can be seen that there is a torsion spring 28 b arranged in the interior of reel 22 b, which is embodied as a hollow reel. Torsion spring 28 b is a weak spring which is always in a tensioned state, even when frame 23 b carrying the one or more openings 230 b is in its lowermost position, so that foil 20 b is always kept in a tensioned state.

As to the operation, it is essentially referred to the embodiment described above with respect to FIGS. 5-9, however, since there is no mechanical connection between the two reels via a belt, torsion spring 28 b is a spring having a high spring rate.

FIG. 13 shows a perspective view of still a further embodiment of a freezer according to the instant invention comprising a specific embodiment of a convection barrier according to the invention. In this embodiment like parts are assigned like reference signs but a letter “c” is added. Accordingly, freezer 1 c comprises a housing 10 c and a door 100 c which is shown in its open position. Convection barrier 2 c comprises an outer frame 24 c, a foil 20 c with a frame 23 c carrying openings 230 c. Foil 20 c extends between the two ends thereof which are mounted to elongate upper reel 21 c and elongate lower reel 22 c, respectively. A motor 25 c drivingly engages an axle 210 c, as can be seen in FIG. 14 showing detail XIV of FIG. 13 in an enlarged view. Axle 210 c is connected to elongate upper reel 21 c for rotatably driving upper reel 21 c with the aid of motor 25 c. A control unit 26 c is provided for operating motor 25 c. Lower elongate reel 22 c is also connected to an axle 220 c. A further motor 28 c drivingly engages an axle 220 c, as can be seen in FIG. 15 showing detail XV of FIG. 13 in an enlarged view. Axle 220 c is connected to lower reel 22 c for rotatably driving lower reel 22 c with the aid of motor 28 c. Also, motor 28 c is connected to control unit 26 c (this connection not being shown in FIGS. 13-15). Control unit 26 c operates the two motors 25 c and 28 c in an asynchronous manner. Depending on the direction of winding foil 20 c, one of the two motors 25 c, 28 c acts as the driving motor while the other motor 28 c, 25 c acts in a manner similar to the return spring. For example, as motor 25 c acts as the driving motor and foil 20 c is wound up onto upper reel 21 c, then foil 20 c is unwound from lower reel 22 c and motor 28 c acts as the return spring, thus continuously keeping foil 20 c in a tensioned state. Or the other way round, as motor 28 c acts as the driving motor and foil 20 c is wound up onto lower reel 22 c, then foil 20 c is unwound from upper reel 21 c and motor 25 c acts as the return spring, thus continuously keeping foil 20 c in a tensioned state.

Finally, it is to be noted that many alternatives are conceivable, for example springs other than torsion springs can be used and the openings for gaining access to the interior of the freezer do not necessarily have to be provided in a frame. Also, it is to be noted that the convection barrier is a separate unit which can be adapted to the respective freezer to which it is to be mounted. Accordingly, the scope of protection is not intended to be limited by the described exemplary embodiments of the invention but rather is defined by the appended claims. 

1. A convection barrier for a freezer, comprising: a foil having at least one opening; storage and transport means for storing and moving the foil to transport the at least one opening to a desired position to allow access through the at least one opening to the interior of the freezer at the desired position, and tensioning means for continuously keeping the foil in a tensioned state.
 2. The convection barrier according to claim 1, wherein the storage and transport means further comprise two reels to which the ends of the foil are mounted and between which the foil extends, as well as a drive for rotating the reels so as to wind up or unwind the foil to transport the at least one opening to the desired position.
 3. The convection barrier according to claim 1, further comprising a frame, the frame being insertable in the foil at a location between the ends of the foil such that the at least one opening for allowing access to the interior of the freezer can be transported to the desired position.
 4. The convection barrier according to claim 2, wherein the drive has a motor connected to one of the two reels and the tensioning means has a return spring connected to the other one of the two reels for continuously keeping the foil in a tensioned state.
 5. The convection barrier according to claim 4, wherein the drive further comprises a belt engaging both of the two reels and the return spring has a low spring rate.
 6. The convection barrier according to claim 4, wherein the return spring has a high spring rate.
 7. The convection barrier according to claim 4, wherein the return spring is a torsion spring.
 8. The convection barrier according to claim 2, wherein the drive and the tensioning means comprise two motors, one of the two motors being connected to one of the two reels and the other motor being connected to the other one of the two reels and a control unit for operating the two motors in an asynchronous manner so as to continuously keep the foil in a tensioned state.
 9. The convection barrier according to claim 1, wherein the foil is made from polytetrafluoroethylene.
 10. A freezer comprising a housing and a door, the housing having an opening allowing access to the interior of the freezer through the opening when the door of the freezer is open, wherein the convection barrier of claim 1 is arranged on the freezer such that the opening allowing access to the interior of the freezer is covered by the foil.
 11. The freezer according to claim 10, wherein one or more motors or a belt of the convection barrier are mounted to the freezer outside its housing. 